This invention relates to contact members for electrical switching devices, in particular contactors, having a linear power supply conductor and an arc runner disposed at a distance from the contact face of the linear power supply conductor and partially guided around this contact face.
In known contact members, the arc runner of the contact member has a U-shaped design. The unattached end of the arc runner receives the electric arc which runs in the plane of the contact face. The U-shaped part of the arc runner is displaced away from the point of contact parallel and lateral to the contact face. The other end of the U-shaped arc runner is used to secure the arc runner.
Such a contact member is disclosed in DE-OS 33 37 515. In practice, this type of contact member has operated satisfactorily. However, the step-shaped power supply conductor may become mechanically deformed in large contactors having considerable amperages, thus possibly affecting the contact closure.
Block-shaped contact members are disclosed in U.S. Pat. No. 3,211,867. However, the arc runner is screwed onto the front side of the power supply conductor. An insulting layer is arranged between the arc runner and the power supply conductor so that the power supply conductor and the arc runner have a peaking-effect on the actuation of the electric arc. The distance between the two branches of the U-shaped arc runner is relatively small in this case and thus the driving effect on the electric arc is not particularly great. In addition, the contact face lies practically in the same plane as the entire arc runner, so that the movable contact member requires precise guidance to prevent the contact face of the movable contact member from coming to rest on the arc runner.
A similar contact member is described in DE-OS 28 03 249. Here, the conductor also has a U-shaped design. This contact member is limited to applications requiring devices having minimal current carrying capacity. When there are high currents, the U-shaped conductor causes the connecting bridge to become disengaged. There is a need for an improved contact member that withstands large mechanical stresses.